1. Field of the Invention
The present invention relates to a tool changing apparatus for changing a punch and die each mounted on a upper and lower turret disk of a turret punch press, and, in particular, to a tool changing apparatus which prepares in advance a plurality of punches and dies to be changed to meet the requirements of a subsequent process.
2. Description of the Prior Art
A turret punch press includes upper and lower turret disks each rotatably mounted on a frame of the punch press in opposition to the other disk; a large number of removable punches and dies are mounted on the upper and lower turrets respectively. The turret punch press of this configuration performs a punching operation on a plate workpiece by means of the large number of punches and dies on the upper and lower turret disks, and is capable of performing punching operations of a wide variety of shapes at good efficiency.
However, in recent years, punching operations of more wide variety of shapes are required to be performed, and punches and dies of more wide variety of shapes are required than are mounted on the upper and lower turret disks. Hence, there is a requirement for a tool changing apparatus for automatically changing the punches and dies on the turret disks.
Apparatuses for changing the punches and dies on the turret disks have been disclosed, for example, in U.S. Pat. Nos. 4,165,669 and 4,624,044. In the configurations of the tool changing apparatus given above, however, from the structures by which the punch holder and die holders are changed on the turret disks extensive modifications are required in the turret disks or in the punches and dies themselves.